Serena Williams is on the cusp of making Grand Slam history, 19 years after her first appearance at the Australian Open -- with only her greatest rival, sister Venus, able to stop her.

The 35-year-old American made her Grand Slam debut in Melbourne way back in 1998 and won the first of her major titles at the US Open a year later.

She has since accumulated 22 over an astonishing career, matching Steffi Graf's Open-era record. One more on Saturday -- her seventh in Australia -- and she will hold the record outright, with only Margaret Court's all-time mark of 24 left to achieve.

Williams has refused to talk about the possibility of finally surpassing the German, after intense pressure over the long-standing record took its toll at last year's US Open, when she lost in the semifinals.

But she now has a golden chance of further cementing her place in history, and at the same time reclaiming the top world ranking that Angelique Kerber seized from her last year.

"It is what it is. Like I said from the beginning, I don't really talk about that any more," Serena said when pressed on what breaking the Graf record would mean.

Intriguingly, it is her older sister who could ruin her day, with Venus, 36, turning back the clock to make her first Grand Slam final since Wimbledon in 2009.

It was Venus who knocked Serena out in round two on her Grand Slam debut 19 years ago, and they have since played eight major finals against each other.

Serena leads 6-2 in those finals, and has an overall 16-11 win-loss record against her sibling.

While reluctant to speak about making history, she is happy to dwell on another all-Williams final, heaping praise on Venus.

The elder Williams has beaten injuries and overcome Sjogren's syndrome, a rare, energy-sapping autoimmune disorder, to reach a 15th Grand Slam final, nearly eight years after her last.

"After everything that Venus has been through with her illness and stuff, I just can't help but feel like it's a win-win situation for me," she said.